Tablet compressing machine



Jne 2, 1936. c. J. WESTIN ET Al. 2,043,086

TABLET coMPRsLN MACHINE Filed April 7, 1934` 4 Sheets-Sheet 1 I o A 27l' f 6,4 /8 30 m l lo 0 'A' IU /2 I June 2, 1936. c. J. wEsTlN ET Ax.2,043,086

TABLET COMPRESSING MACHINE Filed April '7, 1934 4 Sheets-Sheet 2 (slr/Pmff June 2 1936- c. y.1. wEsnN ET Al. 2043,086

TABLET COMPRESS I NG MACHINE Filed April '7, 1934 4 Sheets-Sheet 3 gWVM/roes June 2, 1936. Q J, wEs-nN ET AL I 2,043,086

TABLET coMPREssING MACHINE Filed April 7,' 1934 4 Sheets-Sheet 4 S. t v@kwam/gy. k.

Patented June 2, 1936 PATENT oFFlcE TABLET COMPRESSING MACHINE CharlesJ. Westin and Albert Donaghy, Sr., Philadelphia, Pa., assignors to F. J.Stokes Machine Company, Philadelphia, Pa., a corporation oi'Pennsylvania Application April 7. 1934, Serial No. 719,508

6 Claims.

'I'he present invention relates to tablet-compressing machines which maybe of the rotary type, and pertains particularly to new and usefulimprovements in the principles of construction which result in economyof manufacture,

greater convenience and `eiiiciency .of operation, and which materiallyincrease the production rate of the machine.

Features of .our invention are new and improved means for holding andadjusting the powder feed frame or grid; new and improved means foradjusting the mold-fill or weight-adjuster; new and improved means andmethods for the prevention of dirt around the machine and for dustremoval, or for both; and other features relating to details ofeconomies of construction and operation which will denitely appear fromthe description to follow.

In the drawings:

Fig. 1 is av perspective lview of our device with housing 28 omitted; Y

Fig.` 2 is a diagrammatic and schematic development showing parts of themachine and the way in which they operate, with parts shown incross-section;

Fig. 3 is -a plan view of the grid, indicating the adjacent parts of themachine;

Fig. 4 is a side view of the grid and the moldiill or weight-adjustercam, with parts in vertical cross-section; and

Fig. 5 is a view in side elevation of the upper part of our machine,with parts in vertical crosssection.

In that embodiment of our invention chosen for illustration in thedrawings, there is shown a machine of this general type consisting of aframe I I provided with a base I2, a stationary table I3 with a centralspindle I4 (Fig. 5) on which a rotating mold tableor head is mounted.The head I5 is rotated in the direction in dicated in Figs. 1 and 2 bythe arrow A, as, for example, by a worm-gear I6 (Fig. 5) attached tohead I5 and co-operating with a worm (not shown) mounted -on shaft I8,which is driven from any convenient source of power. As is best seen inFig. 5, the head I5 is of such construction that a number of 'rings orannular disks are superimposed with smaller vrings or necks in between,forming a structure of several stories and of diameters to suit theco-acting mechanism.

A pluralityof apertures are spaced around the head and cut y clearthrough the several stories,-

to form bearings and seats for` the plurality of upper punches 20,.lowerpunches 2l and molds 22. The punches are caused to co-operate withgrid 21 is mounted on housing 28. Grid 21 is yof the center line of'molds 22.y At its oitake end, yor rear end in the direction of rotationof ta- (Cl. 10V-17) the mold 22 through cam tracks (best seen in Fig.2); 23 for the upper, 24 for the lower; or through the upper compressingroll 25 and lower roll 26.

Fig. 2 shows step-by-step in sequence the functions of each set ofpunches for a complete revolution of 360 of the head I5.v The degreesmarked along the top are arbitrarily chosen and merely serve the purposeof showing the synchronized action of the parts. At the 0 line, thelower punch 2| starts down, opening the mold cell and the powder iiowsin, completing the lilling at about where the punch again rises, liftingsome of the powder out of the mold, the excess being scraped'off at 140.-From this point the lower punch may travel straight or be lowered asthe case may be, until it strikes the roller 2B at the same time, orapproximately so, that the upper punch 20 strikes the roller 25 and thepowder is compressed into a tablet at 270. At the 330 line, the tablethas been lifted out of the mold and rides of! the mold table 30 onto thedischarge chute 31 (Fig. 3) at about 350.

Referring to Figs. 3 and 5, a feed frame or 25 stationary in respect tothe rotating head I5 and the mold-table 30 thereon but extends in overthe mold-table, so that the mold table forms the bottom of the grid and,as the head rotates, new molds are successively presented under the gridforA iilling. Grid 21 consists of a labyrinthian structure formed bywalls |21, having openings |28 therein alternately spaced on oppositesides ble I5, grid 21 carriesa scraper I 29, which projects through alslot in the outer wall of grid v 21, and which is pressed by a spring|30 into contact with the surface of mold table 30.

Grid 21 receives the material from hopper 20' 40 and, because of itslabyrinth-like'construction (Fig. 3) and the co-operating effectsbetween the labyrinth and the rotation of the mold-table 30 underneath,the material moves back-and-forth over the molds v22, and, as the punch2l recedes 45 down from the ejecting position opening the mold-cell toits full capacity, the material iiows into this cell land iills it. Thegrid always maintains a surplus amount of material (indicated at B inFig. 4) above the mold and the action of 50 punch 2I is such that themold-cell will receive more material than is needed for the tablet to becompressed but the surplus in the grid, together with the excess powderplaced in the grid, is scraped 01T by scraper |29 as the punch 2| 55have the supporting means so arranged that the grid 21 may quickly beremoved from the machine or detached from the support 38 on housing 28without disturbing the adjustment. This can readily be done with thearrangement of.

parts as shown. Heretofore, using a plain stud or screw rigidly attachedto lug 36 on housing 28, it would cause a very undesirable mess and alotof wasted material when opening or removing housing 28 in order to getin to gear I6 and punches 2|, which frequently is a necessary op-leration. With the novel arrangement of the double threaded cap orthimble 35 supporting the bolt 82, which is clamped to thelug 83 of grid21, it is possible to adjust and set the grid at the desired level and,when necessary, to unfasten it from 88 and open housing 28withoutdisturbing the powder on mold-table 80. The bolt 82 is thereforemade of such a length that it does net reach down to the support 36 buthas a sufficiently free, but threaded, space 32a above cap 88, so thatthe cap 85 may be screwed-up on 82 when unscrewing 88 from 88 to clearthe top of 28. This is accomplished by having the two threads, that is,the thread 82a, on bolt 82 and 88a on cap 38, so arranged that they willcooperate properly. Both threads must be cut the same hand, eitherleft-hand or right-hand, and may be of the same pitch, for example, I3threads per inch, but we prefer to make 82a of a finer pitch than 88a;for example, I8 threads per inch. while 88a is cut with I'threads perinch. This 4 is so that, in unscrewing cap 85, it will slightly lift thegrid 21 away from the mold-table 30, instead of pulling the grid 21 downand clamping it against the mold-table 80, thus jamming the cap 85 andmaking it impossible to unscrew it, which vwould be the case if therelative arrangements of the threads were reversed. The grid 21 isadjusted and set by nrst tightening cap 85 and, with lock-nut 34loose,.the support 82 can be adjusted to hold the grid at the desiredlevel. Then clamp the lock-nut 34 tightly and, when the cap 85 isunscrewed to release the grid 21, itwill return to exactly the sameoriginal position when again tightened in 38.

Referring to Fig. 4, our invention embodies some new kand. usefulimprovements in the construction and operation of the weight-adjustingmechanism or cam. The cam 48 has a long and gentle slope, providing aneasy and gradual rise for punch 2| as it is lifted'to form the propercell depth, regardless of the height to which the punch 2| may be liftedwithin the range of the machine. Cam 48 has a face 48a in the shape of aring sector, as seen in plan view, Fig. 3,'on a radius conforming to theradius ofthe punch centers, as seen in plan view. and cam. is adjustablein a slot or recess 44 of the stationary table I8 and support 48. Thecam 48 is provided ing or lowering cam 48 and is held in the desiredvposition by screw 41 because of the collar 48, on the one side, andhand-wheel 5| on the other side of the support 48. A spring 52 may beusedV as a lock to prevent the screw from turning accidentally. 5Heretofore, instead of the long ring sector 40a. which provides a gentleslope covering the complete range of adjustment for theweight-adjustment, a plug or disk was used, which necessarily waslimited in diameter and, therefore, 10 only had a short and abrupt camsurface, usually requiringa series of auxiliary cams or wedges in frontand back in order to cover the complete range of adjustment. In additionto the above inconvenience of having to change wedges, it l5 wasnecessary, when operatiim at maximum production speeds, to provide ahold-down for the punch to prevent the punch from jumping oif the cam asit reachedthe apex, which jumping would cause uneven weight of tabletsand necessitate 20 operating at reduced speeds. By the use of ourinvention, all the above diillculties are eliminated.

We have also found it desirable to'provide a bridge 43 closely followingthe inside outline of 25 cam 40 and fastened to the top of table I8, toprevent the punch from dropping down below the top of table I3 in casethe slot 44 should happen to be wider than the diameter of the punchheads. It will be noticed that the cam is 30 comparatively narrow, sothat the punch head extends about one-third over the edge of the cam.Slot 44 may, of course, be machined to a nice flt with cam 48, in whichcase the table would Y support the punch, but for the sake of 35 economyin manufacture slot 44 is cored at the time of casting the table andcan, therefore, not be held to such close dimensions that it willfurnish lsuflicient side support for the punch when the low points ofcam 48 areI below the table top. 40

The bridge 43 nicely serves the purpose of cooperating with cam 48 informing a continuous support for the punch.

Although materials compressed into tablets are supposed to be granular,they usually contain a 45 certain percentage of fines as well as dustand, while the grid 21 is constructed so as to confine as far aspossible all the material and prevent any of it from escaping,l we findthat in machines of this type, where large quantities constantly 50 arein motion, considerable dust is produced and will accumulate around theworking parts of the machine. 'I'his dust mixes with 'the lubricant usedon the moving parts, creating avery dirty and undesirable condition.With some materials, 55 the dust has a tendency to absorb the oil in thelubricant, thereby quickly drying the surfaces which results inexcessive friction, causing the punches to bind in their bearings, thegearing to wear out, and, in general, is a source of serious ou troubleand expense. Our invention overcomes 4these difficulties by the novelarrangement of making head I5 and housing 28 co-operate to the extent of4preventing dust from accumulating on mold-table 88 and-punch bearings8l, and 65 keeping dust out of the gearing and the other parts withinthe housing. It will be noticed that v the head I5 is constructed sothat mold-table 38 isof a larger diameter thaxnpunch bearings 8| and,therefore, extends out over the punch bear- 70 ings, and any granulatedmaterial dropping oif table 30 will fall on the incline 82 of housing 28and slide .down into the gutter away from the rotating head l5.Furthermore, bearings 8| are provided with a shelf which extends outover the edge 83 of housing 28. Dust and dirt scraped oi this shelf 8|will, therefore, drop onto the incline 82 and also slide down thegutter, where all of it can be collected and conveniently removedwit-hout interfering with the operation of the machine. v

Most of the dust is created at the ycompression point, where a. puff ofdust is carried up out of the mold 22, as well as down through the mold,by the air expelled in the process of compressing the tablet. These puisof dust would iloat around and settle all over the machine, as well asall over the room, unless removed at the source. By providing aneffective suction system mounted on the frame of the machine or on thehousing 28, as shown, we have eliminated this source of trouble. Thesuction system may consist of two nozzles. and 85 connected to a.suction fan or dust-collecting system, or the two nozzles may becombined into a double nozzle, asshovm in Fig. 5, and piped to thevexhausting arrangement (not shown). When expensive material is beingcompressed, a considerable saving is effected by collecting the dust andmixing it with virgin materiai for re-use.

By the suitable arrangement of protruding shelves on the head I5, incombination with a properly constructed housing 28 and effectivelyplaced suction nozzles, the machine is .kept clean, avoiding the lossesotherwise caused by frequent shut-downs for cleaning and repairs.

We do not intend to be limited save as the,

scope of the prior patents and of the attached claims may require.

We claim:

l. In a tablet machine, a stationary table, first means for conveying aplurality of molds and a plurality of punches for co-operation with saidmolds, second means for compressing material between pairs of saidpunches, a grid mounted adjacent said molds so that said molds aremovable relative thereto, a hopper mounted to feed material to saidgrid, bolts forming supports for said grid, caps having screw-threadedengagement with said bolts and having screw-threaded engagement' withsaid table, a cam projecting through an opening in said table forco-operation' with the llower ones of said plurality of punches, saidcam-having a face in the shape in plan of a' ring sector on a radiusconforming to the radius of the punch centers, and located so as toraise the lower ones of -said plurality of punches and to adjust theamount of material received by said molds, and means mounted on saidtable adjacent said second means at the point of compression of saidpunches ior-removing dust from around said molds and said punches.

2. In a tablet machine, a stationary table.-a mold' table mounted formovement on said stationary table and carrying therein a plurality ofmolds and a plurality of punches for co-operation with said molds, agrid mounted on said stationary table above that portion of said moldtable carrying said plurality of molds, bolts forming supports for saidgrid, and caps having screwthreaded engagement with said bolts andhaving screw-threaded engagement withsaid stationary table, whereby saidgrid may be disengaged from said stationary table by unscrewing saidcaps.

3. In a tablet machine, a stationary table, a mold table mounted formovement on said stationary table and having a plurality of molds and aplurality of punches for co-operation with said molds therein, a housingmounted on said stationary table and encircling and underlying portionsof said mold table, a. grid mounted above that portion of said moldtable having the molds,

bolts forming supports for said grid, and caps having screw-threadedengagement with said bolts and having screw-threaded engagement withsaid housing so that said grid may be rejacent said mold table, capshaving screw-thread- I ed engagement with said bolts and formingsupports therefor, and a housing having screwthreaded engagement withsaid caps, the screwthreads between said caps and said bolts being of nogreater pitch than the screw-threads between said caps and said housing,said housing forming -a support for said caps and for said bolts andsaid grid thereon.

5. In a tablet machine, a stationary table. a mold table having aplurality of molds and a plurality of upper and lower punches therein, acam extending through a perforation-,fin said stationary table andhaving a face in the shape in plan of a ring sector on a radiusconforming to the'radius of the centers oi said punches, a

support for said cam, andl screw-threaded means interposed between saidcam and said support for adjusting the height of said cam.

6. In a tablet machine, a stationary table, al

mold table having a plurality of molds and a 13.

plurality of upper and lower punches therein, a cam projecting through aperforation in said stationary table for co-'operating with said lowerpunches, said cam having a face thereon which conforms in plan to thepath of movement of

